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Platyhelminthes
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Into which classes are platyhelminthes divided? How are these classes characterized and what are some representative beings of each of them?
Platyhelminthes are divided into three classes: turbellarians (or Turbellaria), trematodes (or Trematoda) and cestodes (or Cestoda).Turbellarians are free-living platyhelminthes and their main representative is the planaria (Dugesia tigrina). Trematodes are parasites, they live inside a host and theRead more
Platyhelminthes are divided into three classes: turbellarians (or Turbellaria), trematodes (or Trematoda) and cestodes (or Cestoda).
Turbellarians are free-living platyhelminthes and their main representative is the planaria (Dugesia tigrina). Trematodes are parasites, they live inside a host and the schistosome (Schistosoma mansoni) that causes schistosomiasis is an example. Cestodes are parasites too, they do not have digestive tubes and their cells are nourished by absorption of nutrients from the host; their most popular representative are the beef and pork taenias (Taenia saginata and Taenia solium) that parasite humans.
See lessIs it possible for a hermaphrodite species to present cross-fecundation?
There are hermaphrodite species of animals and plants that present crossfecundation mainly due to the maturation of female and male structures at different periods.Cross fecundation occurs in planarias, hermaphrodites in which sexual fecundation takes place with male and female gametes from differenRead more
There are hermaphrodite species of animals and plants that present crossfecundation mainly due to the maturation of female and male structures at different periods.
Cross fecundation occurs in planarias, hermaphrodites in which sexual fecundation takes place with male and female gametes from different individuals. These individuals approach their copulating structures and exchange gametes.
See lessWhat are the types of digestion and of digestive system of platyhelminthes?
Flatworms have incomplete digestive systems and they present extracellular and intracellular complementary digestions.
Flatworms have incomplete digestive systems and they present extracellular and intracellular complementary digestions.
See lessHow can asexual reproduction in planarias be described?
Planarias can divide themselves asexually by transversal bipartition due to the great regeneration capability of their tissues. When they attach to a substrate they can induce a constriction in their middle region and the body is then separated into two parts and each of these parts gives birth to aRead more
Planarias can divide themselves asexually by transversal bipartition due to the great regeneration capability of their tissues. When they attach to a substrate they can induce a constriction in their middle region and the body is then separated into two parts and each of these parts gives birth to a new individual as tissue regenerates.
See lessHow many germ layers originate the body of platyhelminthes? In relation to this characteristic how are these animals classified?
Platyhelminthes are the first triploblastic animals (remember that cnidarians are diploblastic), i.e., they present three germ layers: ectoderm, mesoderm and endoderm.
Platyhelminthes are the first triploblastic animals (remember that cnidarians are diploblastic), i.e., they present three germ layers: ectoderm, mesoderm and endoderm.
See lessHow is gas exchange done in flatworms?
Platyhelminthes exchange gases exclusively by diffusion through their body surface. This is only possible because all cells are localized relatively near to the exterior since gases diffuse cell by cell (the flat shape of these worms is a feature that allows this type of respiration).
Platyhelminthes exchange gases exclusively by diffusion through their body surface. This is only possible because all cells are localized relatively near to the exterior since gases diffuse cell by cell (the flat shape of these worms is a feature that allows this type of respiration).
See lessWhat is an example of freshwater flatworm? Due to that habitat what is the physiological problem that these animals must solve?
Platyhelminthes of freshwater, like planarias, have an internal environment much more concentrated in solutes than the exterior and so they present a tendency to gain water. These organisms then need a drainage system to avoid cell death caused by excessive water.The problem is solved by the presencRead more
Platyhelminthes of freshwater, like planarias, have an internal environment much more concentrated in solutes than the exterior and so they present a tendency to gain water. These organisms then need a drainage system to avoid cell death caused by excessive water.
The problem is solved by the presence of protonephridia located along longitudinal channels in the animal body. Protonephridia have ciliated cells, the flame cells, that push water outside the body through excretory pores.
See lessIs the nervous system in platyhelminthes more or less sophisticated than in cnidarians? What are the main neural structures found in flatworms? How is this neural organization important for the diversity of biological niches explored by species of the phylum?
Platyhelminthes present a more sophisticated nervous system than cnidarians, as the first neural chords with ganglia (grouping of neurons) appear, a characteristic of the evolutionary process of increased nervous complexity. In platyhelminthes one can note the beginning of the cephalization process,Read more
Platyhelminthes present a more sophisticated nervous system than cnidarians, as the first neural chords with ganglia (grouping of neurons) appear, a characteristic of the evolutionary process of increased nervous complexity. In platyhelminthes one can note the beginning of the cephalization process, with a concentration of neurons (nervous cells) in the anterior portion of the body and the appearance of photoreceptor cells in the ocelli.
With the increased capacity of these animals to perceive and to interact with the surrounds due to the increased complexity of their neural complexity, it is possible to find platyhelminthes in a variety of environments, including the terrestrial, and with diverse ways of life, like those that are parasites and those that are free-living.
See lessPoriferans and cnidarians do not have excretory systems. Do platyhelminthes have an excretory system?
Platyhelminthes have a primitive excretory system made of flame cells (also called solenocytes), excretory ducts and excretory pores.
Platyhelminthes have a primitive excretory system made of flame cells (also called solenocytes), excretory ducts and excretory pores.
See lessAre flatworms monoecious or dioecious?
There are monoecious hermaphrodite flatworms, like planarias and taenias, and there are dioecious (having male and female individuals) species too, like schistosomes.
There are monoecious hermaphrodite flatworms, like planarias and taenias, and there are dioecious (having male and female individuals) species too, like schistosomes.
See less